Regular Expressions

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What is the secret behind ^ and $ which makes understanding expressions easier?
- ^ represents "starts with" so it's ALWAYs First
- ^Dal Never d^al or dal^
- $ represents "ends with" so it's Always last
- Dal# never #Dal or D#al
So if you search ^Dal# the result can only be Dal since it starts with and ends with "Dal"
'*', '+', and '?', What do these symbols mean?

"zero or more", "one or more", and "zero or one."
What is the difference between ^ and [^] as in ^me or [^me]

^me means that it must start with "me" but [^me] means that it can't contain "me"
What do regular expresssions need to be enclosed by, including variables

"/ /"
What PHP function checks for matches?

preg_match()
Added to look for something at the end of a string

$ as in bob$ matches dumbbob but not bobdumb
Added to look for something at the start of a string

^ as in ^cat matches catalog but not concatenate
Wildcard

. period
Wildcard for zero or more

*
Look for either a A or B make sure you have the symbol for or

(A|B)
Requires that there be one or more of the characters it follows

+ as in (a|B) must have an a or B
Search for something in a range

[a-z]
Set the range of a number of occurences. As in give me 2-5 A's
- {2,5} as in A{2,5} is looking for
- AA
- AAA
- AAAA
- AAAAA
Exclude characters....

[^] as in [^A] means no A can be in the search
When you use exclusion brackets what is special about them?
- Everything except - ][ and ^ are taken literally. thus
- you get a mishmash, since you can't use separaters
- a-zA-Z0-9
Wildcard for 0 or 1

?
Escape character so you can use a . or a ^ or a $

\

Author

dalbabes

107003

Card Set

Regular Expressions

Description

Regular expression help

Updated

2012-07-26T15:48:37Z